This is an ongoing project to study the regulatory mechanisms of eicosanoid synthesis in vascular and blood cells. We have shown that cell-cell interaction plays a major role in PGI2 generation at vascular injury sites. Platelet-derived PGH2 is taken up by subendothelial smooth muscle cells which convert it to PGI2. The platelet-derived PGH2 is also utilized by lymphocytes to synthesize PGI2. The goal of this proposal is to further evaluate the regulatory mechanisms at cellular and molecular levels. Preliminary data from our work reveal that phorbol ester and interleukin-2 elicit a highly selective stimulation of eicosanoid synthesis by cultured human and bovine endothelial cells. Stimulation of eicosanoid synthesis by these compounds appears to depend on de novo protein synthesis. We plan to test the hypothesis that phorbol ester and IL-2 stimulate eicosanoid synthesis via de novo synthesis of PGH synthase. The regulation may reside at the level of transcription. We have observed that unlike its effect on endothelial cells, PMA stimulates platelet to synthesize 12 HETE and the effect is enhanced calcium ionophore. We postulate that the mechanism involved in platelets is due to activation of 12-lipoxygenase. We consider it important to perform additional studies on other non-dividing cells such as macrophage and cells from brain. To test the hypothesis, we propose four specific aims. Biochemical, molecular biology, and cell biology techniques will be employed to provide answers to each of the specific aims. The information derived from this project will be valuable for understanding the generation of eicosanoids which play key role in modulating cerebrovascular thrombosis and brain ischemia. It will shed light on the cell types that contribute to eicosanoid synthesis and the different mechanism underlying various stimulatory conditions. We hope that this basic investigation will enable us to develop better therapeutic strategic for controlling cerebral infarction.